Police 'worried'

"His disappearance is totally out of character and we are worried that he may have become lost down one of the city's alleyways or side roads as he tried to find a taxi home.

"It is quite possible that Benjamin may have got lost while looking for a taxi rank and may be lying injured in an alleyway or a side street, so I would urge business owners to check their bin yards and areas behind their premises.

"I would also encourage anyone who saw Benjamin in or around the city centre, particularly taxi drivers or employees working in licensed premises, to contact us immediately."

Benjamin's last contact with friends or family was at around 0130 GMT, when he sent a text message to his mother.

He is described as white, about 5ft 4in, slim, with mousey blond shoulder-length hair. He was wearing white Converse high-tops, grey jeans, a black T-shirt and a grey fleece jacket.